1. Field of the Invention
This invention relates to a cutting machine.
2. Description of the Related Art
A known mower of this type has a traction element which extends between the hitching structure and the support beam. This traction element comprises a pipe, provided at its longitudinal end opposite the hitching structure with slot extending in the direction of said pipe. A pin, attached to the hitching structure, goes through the slot which allows a relative movement of the traction element relative to said pin over a length equal to that of the slot.
The traction element also has a tie rod slidably mounted in the pipe and whose free end is connected to the support beam by a retaining pin. The latter extends parallel to the direction of work and can be pivoted around its geometric axis.
The guiding of the tie rod relative to the pipe is provided by two centering rods lengthening said pipe. A disk integral with the tie rod has two holes for the passage of the centering rods. Moreover, between the disk and a ring carried by the free ends of the centering rods extends a compression spring whose force tends to separate the disk from the ring. By so doing, the compression ring tends, during work, to reduce the length of the traction element and to lighten the cutting mechanism.
To cancel the action of the traction element for setting down of the mower, it is provided that the end of the tie rod which is inside the pipe just abuts against a pin put in place by the user for this purpose. In this way, when this known mower is to be set down, it is advantageously possible to pivot the hitching structure relative to the support beam around the axis of the first journal within the limits allowed by the slot. This substantially facilitates the hitching of the mower to a tractor.
Nevertheless, this known mower exhibits some drawbacks.
First, to lighten the cutting mechanism correctly during its displacements in height, the prestressing length of the compression spring must be relatively large, therefore its offload length must also be large.
Moreover, taking into account the extent of the prestressing necessary for a sufficient lightening of the cutting mechanism, it is not very easy to remove the compression spring, in particular following the breaking of a coil of the spring.
An additional drawback of this known mower appears during transport, where the support beam pivots relative to the hitching structure around the axis of the first journal under the effect of the contour of the ground combined with the actions of the spring and the weight of the cutting mechanism, resulting in a continual swinging of the cutting mechanism.